Evaluation of the reduction in carbonyl emissions and ozone formation potential from the exhaust of a heavy-duty diesel engine by hydrogen-diesel dual fuel combustion

In this study, diesel engine was fueled by multi-fuels, including conventional diesel and 0, 0.6 and 1.2 vol% hydrogen and operated at low to high engine loads. Low molecular weight carbonyls, such as formaldehyde, acetaldehyde, and acetone, contributed 79.2-87.2% of total carbonyl compounds which are the more prominent when the engine operated at low load. With 0.6 and 1.2 vol% of hydrogen addition, formaldehyde decreased 10.4-10.9% at idling condition. As the load increases 25, 50 and 75%, the formaldehyde decreased by 2.93-25.1, 5.91-25.8 and 2.28-40.5%, respectively. The same reduction phenomenon can also be observed from acrolein, acetone, propionaldehyde, crotonaldehyde and 2-butanone & butyraldehyde emissions. The highest ozone-formation potential (OFP) from multi-pollution emissions was found at idling operation. The high OFP could be reduced by increasing hydrogen additions and eventually approached the lowest level with 1.2 vol% hydrogen addition at middle to high engine load. Nevertheless, the diesel engine with hydrogen addition could reduce a certain amount of CBC emission and OFP at engine idling operation.